TYP: annotation of __init__ return type (PEP 484) (pandas/utils)

[nafarya]

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According to documentation pandas uses PEP484 for type hints.
PEP484 states that __init__ function should have -> None return type annotation.
In this PR I added return type annotation to __init__ functions in pandas/utils module.
Thanks!

[NickCrews]

@nafarya Hi! Thanks for this! I'm wondering if there is a way to configure our code checks so that this is caught automatically? ie can black or flake8 somehow catch this? That seems like the golden standard, if possible, so that the entire codebase is consistent.

[nafarya]

@nafarya Hi! Thanks for this! I'm wondering if there is a way to configure our code checks so that this is caught automatically? ie can black or flake8 somehow catch this? That seems like the golden standard, if possible, so that the entire codebase is consistent.

Hi! Thats great idea and I think it should be possible! Maybe it could be done the same way as you check for PEP 8: via https://github.com/pep8speaks

[NickCrews]

Floated the idea to black here: psf/black#2913

[phofl]

Please wait for #46283 (comment)

[jreback]

thanks @nafarya